The human Y chromosome is an ideal chromosome for a complete sequence determination. It is one of the smallest chromosomes and consists of only 1-2% (or about 60 Mb) of the human genome. Because of its genetic simplicity, the actual informative sequence may be as little as 20 Mb. The recent construction of a detailed deletion map with 43 intervals defined by STSs and DNAs of individuals with naturally occurring deletions and a YAC-based physical map of its euchromatic region have greatly advanced our knowledge of this chromosome. This development has raised the possibility that the complete genetic content of the human Y chromosome can be determined in the near future. However, in order to accomplish this goal, several issues need to be resolved before vigorous efforts can be implemented worldwide. First, numerous partial and/or regional maps in YACs and cosmids generated in several laboratories have to be aligned with both deletion and physical maps. The successful completion of this task will confirm the validity of the published maps and expand the resolution to a higher level. Second, the generation of a consensus physical map will enable investigators to focus on particular segments of the chromosome on which several important loci, such as status and spermatogenic factors, have been mapped. Third, an agreement on the management and distribution of research materials will further enhance the possibility of applying positional cloning strategies for the identification of ESTs on the human Y chromosome. To accomplish the above objective, we propose to conduct an international workshop on human Y chromosome to be held on April 9-10,1994 on the campus of Cambridge University, England. The workshop will focus on alignment of cosmid and YAC contig maps at various subregions, the fine mapping of various genetic loci, discussion of positional cloning strategies for candidate gene identification, and the establishment of mechanisms for the management and distribution of research materials and data sharing for the human Y chromosome. Since a specific conference on the Y chromosome has not been held for over 5 years, this workshop will be critical for workers in the field of Y chromosome research. It will allow interested investigators to work together and establish the Y chromosome to be the first human chromosome whose genetic content will be completely dissected.